This disclosure relates generally to the field of wager games and more particularly to methods and apparatus that facilitate the use of “stacked” and “expanding” symbols of a reel-type wager game. The methods are applicable in a variety of game playing formats, for example physical slot machines, electronic video gaming terminals, and computer workstations playing wager games over a computer network.
In reel-type games such as slots, one or more reels are provided, each of which contain a multitude of symbols distributed around the circumference of the reel. When a player places a wager (e.g., by placing a coin in the machine) they are then permitted to spin the reels. Each reel comes to rest, typically with either one of the symbols, or a space in between the symbols, in alignment with a pay line. The player wins according to whether a particular winning symbol or combination of symbols is present on the pay line. In a simple three-reel slot machine game, the pay line is the horizontal line going across the middle of the reels. In other reel-type games, such as an array of 3×5 symbols which all change or “spin” during a turn of play, the “pay line” refers to a particular combination of positions of symbols in the 3×5 array which are used to determine if a winning result was achieved; for example, each of the three rows of five symbols could be a different pay line, making three pay lines in total.
The game of slots can be played on a video gaming terminal with a graphical user interface, e.g., a dedicated gaming machine such as found in a casino. In the case of a video gaming terminal, the user interface displays an image of a set of reels. Animation effects are used to simulate the spinning action. A computer software program, which may be resident in the video gaming terminal, randomly generates a result for a simulated spin of the reels, and the result is presented on the user interface.
Slots games are also played over a computer network, e.g., by a player using a personal computer which has established a connection to a gaming server. In this later situation, the gaming server generates results of play and transmits the results over the computer network to the computer for display.
The popularity of video slot games has increased due to the incorporation of a “wild” symbol into such video slot games. A wild symbol, which is usually the highest-ranking symbol of the game, offers line payouts just like any other symbol and, additionally, substitutes for any other symbol in the game, thereby assisting in making winning results and providing a player with entertainment and additional opportunities to win game prizes.
The wild symbol may be associated with additional properties. In particular, the wild symbol may act as a multiplier, i.e. when the wild symbol forms part of a winning result the corresponding payout in the pay table of the game is multiplied by an applicable multiplier. The multiplier is usually fixed and is given in the pay table. The multiplier may also depend on the number of wild symbols forming part of the winning result.
A stacked wild symbol is one that appears as a contiguous stack of wild symbols on a reel (e.g. three wild symbols appearing as if they were successive symbols around the circumference of the reel), which increases still further the potential of having one or more winning results along one of the pay lines.
An expanding wild symbol is one which visually expands (e.g. by computer-driven animation) to occupy the entire reel display area for a given reel, usually depicted by means of an animated sequence. The effect on a payout is the same as that of a stacked wild symbol that occupies the entire reel display area, but the visual effect of the expanding wild symbol animation is different (for example, a single graphical element may expand to cover the whole reel display, rather than the reel display consisting of a plurality of identical wild symbols).
In all of these prior art scenarios, the appearance of a wild symbol (whether single, stacked or expanding) depends on the results of a single play or spin of the underlying video slot game.
Prior art of interest includes Webb US 2005/0070353; Cuddy et al. US 2005/0075163; Jaffe et al. US 2010/0016071; Berman et al US 2004/0132527; Glavich U.S. Pat. No. 6,955,600 and Naicker et al., US 2009/0111566.